In 2025, the tax calculation for a social security base of 19,900 in Lishui, Zhejiang involves several steps. First, we need to calculate the amount of social security contributions, and then use the personal income tax formula to determine the tax amount.

1. Calculate Social Security Contributions

• Pension Insurance:

• The personal contribution rate is usually 8%. So for a social security base of 19,900 yuan, the personal pension insurance contribution is ​
  ×8%=
  yuan.

• Medical Insurance:

• The personal contribution rate is around 2%. So the personal medical insurance contribution is ​
  ×2%=
  yuan.

• Unemployment Insurance:

• The personal contribution rate is generally 0.5%. So the personal unemployment insurance contribution is ​
  ×0.5%=99.5
  yuan.

• Total Social Security Contributions:

• The total of the above three items is ​
  ++99.5=2089.5
  yuan. Please note that industrial injury insurance and maternity insurance are usually fully borne by the unit, so there is no personal contribution.

2. Calculate Personal Income Tax

• Determine Taxable Income:

• The formula for calculating taxable income is: taxable income = monthly income - 5000 yuan (tax threshold) - special deductions (such as social security) - special additional deductions - other deductions determined by law.

• Assuming there are no special additional deductions and other deductions, and taking the social security contribution calculated above, the taxable income is ​
  −−2089.5=12810.5
  yuan.

• Determine Tax Rate and Quick Deduction Amount:

• Looking at the personal income tax rate table for wage and salary income, for a taxable income of 12810.5 yuan, it falls into the range where the tax rate is 10% and the quick deduction amount is 210 yuan.

• Calculate Personal Income Tax:

• The formula for calculating personal income tax is: personal income tax = taxable income × tax rate - quick deduction amount.

• Substituting the values, we get ​
  12810.5×10%−=1071.05
  yuan.

In conclusion, if the social security base is 19,900 yuan in Lishui, Zhejiang, under the conditions assumed above (no special additional deductions and other deductions), the personal income tax is approximately 1071.05 yuan. However, in actual situations, individual tax amounts may vary due to different special additional deductions and other factors.

want to factor in other deductions like special additional deductions or if you have specific questions about the calculation process, please share those details. I'd be glad to refine the calculation for you.